One reason why this issue has been having less impact is that a bug in some versions of the copy.py code meant it was ignoring the __deepcopy__ stubs and using the pickle logic to copy _sre objects - so, if you run the right python version, compiled regular expressions and match objects deepcopy without problems. On the 2.4 branch (release24-maint), changeset 38430 introduced the bug that prevents the class __deepcopy__ exception-raising stubs being found. As an aside, I don't understand why the _sre objects should be pickleable, but not deepcopy-able.